She is expected to reiterate her warning that “catastrophic harm” will be inflicted to trust in politicians if they fail to implement the result of the referendum.

Mr Fox, a Brexiteer who has swung behind Mrs May’s Brexit deal, told BBC Radio 4’s Today programme: “The Prime Minister will seek to make a statement in the House of Commons today outlining the assurances she had had from the European Union following discussions over the last few days.

“I hope my colleagues will listen to those and recognise the best way forward is to support the Government’s agreement because it delivers on the referendum result and does so in a way that minimises the risks to our economy.”

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With Mrs May’s deal widely expected to fall to a heavy defeat when MPs vote on Tuesday evening, backbenchers in her own party have launched a plan to allow Parliament to frame a “compromise” if she fails to produce a viable plan B.

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Mr Boles told Today it would give the Government three weeks to seek a compromise that can get past the Commons and allow the UK to leave the EU on March 29 as planned.

If that fails, he said, it would give the Liaison Committee “the responsibility to try and come up with its own compromise deal, which would have to go back to the House for a vote”.

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He added: “If the House passed that compromise deal, then the Government would be legally required to implement whatever it was that they had.”

Under our constitution, Parliament can either change the government’s mind or change the government. It can propose legislation for government to take forward & it can amend or block it but back bench MPs cannot take over conducting a complex international negotiation

However, the Liaison Committee chairwoman, Tory Sarah Wollaston, said it had not been discussed with other members and that backbenchers constitutionally “cannot take over conducting a complex international negotiation”.

Former foreign secretary Boris Johnson, meanwhile, criticised “complicated jiggery-pokery” by MPs, warning they were “really playing with fire”.

He told LBC: “I think that people will feel betrayed.

“And I think they will feel that there has been a great conspiracy by the deep state of the UK, the people who really run the country.”

With less than 36 hours to go until the long-awaited vote, Mrs May will say, based on last week’s Westminster drama, that she now believes MPs blocking Brexit is a more likely outcome than leaving without a deal.

Speaker John Bercow sparked uproar in the Commons last week after he selected an amendment from Tory former minister Dominic Grieve which attempts to speed up the process for the Government to reveal what it will do next if the PM’s Brexit deal is rejected.

Mrs May is expected to tell factory workers in pro-Leave Stoke-on-Trent on Monday: “Imagine if an anti-devolution House of Commons had said to the people of Scotland or Wales that despite voting in favour of a devolved legislature, Parliament knew better and would overrule them. Or else force them to vote again.

Four Tory Brexiteers announced at the weekend their support for Mrs May’s Withdrawal Agreement, despite suggestions they could vote against it.

Backbenchers Sir Edward Leigh, Sir Geoffrey Clifton-Brown, Andrew Murrison and Caroline Johnson expressed reservations at backing the deal, but each said they had come to the conclusion to support it.

Mr Murrison is tabling an amendment to the Brexit motion to create a “sunset clause” preventing the backstop extending beyond the end of 2022.

The amendment backs Theresa May’s deal, subject to a legal codicil to the Withdrawal Agreement which states that the backstop must end by December 31 2022.

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“It will introduce a sunset arrangement by which the backstop will fall away.”

Dr Fox added on Today that not leaving was politically “a disaster from which we might not recover”.

He admitted that while no-deal Brexit would damage the economy it was better than staying, adding: “I don’t regard no-deal as national suicide. This is not Dunkirk, this is leaving the European Union.”

But former attorney general Dominic Grieve disagreed, telling the same programme: “It will lead to the break-up of the UK for starters. That seems to me to be a pretty clear indication of a form of national suicide.”